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# Two influenza vaccine doses in a year tracked lower hospital mortality in Brazil
- URL: https://www.coios.me/two-influenza-vaccine-doses-in-a-year-tracked-lower/
- Published: 2026-09-23T12:45:00.000Z
- Updated: 2026-09-23T21:35:15.000Z
- Description: Among patients hospitalised with confirmed influenza in Brazil between 2023 and October 2025, a single trivalent vaccine dose was associated with 10-13% lower adverse outcomes and two doses within a calendar year with 32% lower in-hospital mortality.
- Author: Daniel Ryan
- Tags: Healthcare today, Infectious disease and pandemics, Brazil, #preprint, #confirms, #item, #source-2026-09

The analysis used Brazilian national surveillance records of patients hospitalised with severe acute respiratory infection and confirmed influenza from 2023 to October 2025, taking the number of trivalent vaccine doses received within a calendar year as the exposure. Vaccine uptake among these patients fell from around 70% in 2023 to 40-50% in 2024 and 2025; one dose was associated with 10-13% lower adverse outcomes and two doses with 32% lower mortality, 52% fewer ICU admissions and a shorter ICU stay.

*Why it is interesting: A severity-reducing effect of influenza vaccination in a large middle-income surveillance system, set against a background of falling uptake, though the dose-response pattern invites scrutiny of confounding by access to care.*

Source

[medRxiv, 21 September 2026](https://doi.org/10.64898/2026.09.15.26362995?ref=coios.me)

DOI

10.64898/2026.09.15.26362995

Type

Preprint

Design

Retrospective analysis of Brazilian SARI hospitalisation surveillance records, 2023 to October 2025, Poisson regression on vaccine doses received per calendar year

Verdict

Confirms prior evidence

Driver

[Infectious disease and pandemics](https://www.coios.me/d-infectious-disease/)